Julian is the youngest member of an ancient, malevolent race known as Shadow Men. Despite his truly wicked, mercurial nature and history of terrorizing people for centuries, he experiences genuine love for the first time upon meeting Jenny, first seeing her when she is five years old. Ever since, touched by her goodness and innocence, he has followed and protected her, guarding her from harm, with the intention of ultimately making her his consort. However, when Jenny becomes a teenager and in spite of her love for Tom, Julian finally makes an overt attempt to gain her for himself, luring her into the More Games store and selling her the game which he later brings to life. He does this for two primary reasons: wanting to give her a "chance" to escape him should she defeat him at his own games, and because it is in his very nature to play games of chance with humans. He is not above using force or trickery however to get what he wants, and has mentioned several times that he is even willing to hurt or kill Jenny if necessary. Julian is also shown to hold a personal ire and jealousy towards Tom (and to some extent Zach). However, if Jenny is threatened by forces outside his control, Julian is shown to be highly protective and worried for her, even willing at one point to risk his own existence for her sake.
As revealed in The Kill, like his fellow Shadow Men, Julian was not born but created, his name carved on a special rune stave that gives life to those whose names are carved into it. Additionally, despite his unearthly beauty, Julian will eventually lose his looks and become a deformed creature like the other Shadow Men. His name, Julian, is an admitted alias, derived from the Arabic word "djinn", from which the modern word "genie" comes.